Plastic chuck with highly airtight slider and bag body with the chuck

ABSTRACT

A plastic zipper equipped with a slider, which zipper is imparted with high hermetical-sealability and facility in unsealing and reopening/reclosing. The zipper is capable of detection of its having been unsealed after sealing packaging, and a bag body is fitted with the zipper with a slider attached. The zipper portion is bonded in the plastic zipper equipped with a slider or protrusion portions for slider guide via an easily peelable plastic layer and two different colors are imparted to the resin at the portion to be bonded. The bag body is capable of assuring high hermetical-sealability enabling long-term preservation of contents therein, is easy to open, and is imparted with a function of revealing unjust unsealing as well.

TECHNICAL FIELD

The present invention relates to a highly hermetically-sealable plasticzipper equipped with a slider which zipper is employed in packagingmaterials for foods, pharmaceuticals, electronic part items and thelike, and enables easy opening and resealing, while maintaininghermetical sealability; and to a bag body fitted with theabove-mentioned zipper. It also pertains to a plastic zipper equippedwith a slider which zipper enables detection of its having been unsealedafter sealing packaging; and to a bag body fitted with the zipper justmentioned.

BACKGROUND ART

There are widely employed, as packaging materials for a variety ofarticles in the fields of foods, pharmaceuticals, electronic part itemsand the like, bag bodies each fitted with a plastic zipper. Inparticular, there are widely employed plastic zippers each equipped witha slider because of easiness in opening and closing and its capabilityof resealing. Thus, accompanying the diversification of objects to bepackaged, it follows that higher hermetical-sealability is required ofthe plastic zippers. At the same time, it is desired that the zipper beendowed with the function capable of detection of its having beenunsealed after sealing packaging, since unsealing thereafter due to anunfair purpose or mistake brings about such disadvantages as foreignmatters being mixed in and impaired quality of the content in the bagbodies.

FIG. 9 through FIG. 15 each illustrate an example of a previously knownplastic zipper which is equipped with a slider, and is endowed with highhermetical-sealability and/or function capable of detecting unsealing.

The example as illustrated on FIG. 9 (perspective view) and FIG. 10(cross sectional end view taken along line A–A′ of FIG. 9) point out asystem wherein the top portion of a bag body fitted with a zipper inwhich a bag 9-3 is fitted with a zipper 9-2 and a slider 9-1 is coveredwith a cover film 9-4 bearing perforated line 9-5 so that the portionsof the slider and zipper are overspread therewith, and in the case ofunsealing for the first time, the perforated line 9-5 are cut off andthereafter the zipper is opened/closed by means of the slider. Theabove-mentioned system has simple structure and favorable operability,but suffers from such disadvantages as unfavorable appearance andinferior productivity from the industrial viewpoint.

The example as illustrated on FIG. 11 (perspective view) and FIG. 12(cross sectional end view taken along line B–B′ of FIG. 11) point out asystem wherein a partition film 11-4 bearing perforated line 11-5 isinstalled inside a bag body fitted with a zipper in which a bag 9-3 isfitted with a zipper 9-2 and a slider 9-1, and in the case of unsealingfor the first time, the zipper is opened by means of the slider andthereafter, the perforated line 11-5 are opened. The above-mentionedsystem has favorable appearance and good productivity, but involves sucha problem that in the case of the content being fine particles such aspowder, the partition film portion is plugged up with the fineparticles, thereby making it impossible to smoothly discharge the same.

The example as illustrated on FIG. 13 (perspective view) indicates asystem wherein a bag body fitted with a zipper in which a bag 9-3 isfitted with a zipper 9-2 and a slider 9-1 is subjected to spot welding(13-1) at the top portion of the zipper in a state that the slider is atthe closing position, and in the case of unsealing for the first time,the weld portion is cut away with the slider.

The method as illustrated on FIG. 14 (perspective view) indicates asystem wherein part of a zipper top portion 14-4 bearing perforated line14-5, etc. is cut off in a state that the zipper 9-2 is set at theclosing position of the bag 9-3, a slider is attached to the cutportion, and in the case of unsealing, the zipper top portion 14-4 iscut away along the perforated line.

The systems as illustrated on FIG. 9 and FIG. 11 is advantageous in thatthe hermetical sealability of the bag body can be assured by theadoption of the hermetical-sealed perforated line, whereas the systemsas illustrated on FIG. 13 and FIG. 14, the hermetical sealability of thebag body depends upon the hermetical sealability of the zipper itself,thus making the above-cited systems unusable in applications based onthe precondition of long-term preservation such as retort pouch.

DISCLOSURE OF THE INVENTION

As a result of intensive research and investigation, the presentinventor has developed a plastic zipper equipped with a slider whichzipper has hermetical sealability to a high degree, and furtherfacilitates unsealing and reopening/reclosing; a plastic zipper equippedwith a slider which zipper has, in addition to the aforesaid capability,a function capable of detection of its having been unsealed aftersealing packaging; and a bag body fitted with either of theabove-mentioned zippers equipped with a slider.

The means for solving the subjects are summarized as follows.

-   1. In a plastic zipper equipped with a slider, comprising a pair of    male hook and female hook formed on surfaces of plastic films, a    continuous tightening wall which is parallel to the male hook and    placed inside the male hook and a continuous pressing rib which is    parallel to the female hook and placed inside the female hook; the    continuous tightening wall and the continuous pressing rib are    bonded to each other in a state of the zipper being engaged via an    easily peelable plastic layer which is installed in advance on the    surface of at least one of the continuous tightening wall and the    continuous pressing rib (hereinafter referred to as the “first    aspect of the present invention”).-   2. In a plastic zipper equipped with a slider, comprising a pair of    male hook and female hook formed on surfaces of plastic films; a top    portion of the male hook and a bottom portion of the female hook are    bonded to each other in a state of the zipper being engaged via an    easily peelable plastic layer which is installed in advance on the    surface of at least one of a top portion of the male hook and a    bottom portion of the female hook (hereinafter referred to as the    “second aspect of the present invention”).-   3. In a plastic zipper equipped with a slider, comprising a pair of    male hook and female hook formed on surfaces of plastic films, and a    pair of protrusions for slider guide which are installed parallel to    each of the male hook and female hook on the side of the opening    portion; the pair of protrusions for slider guide are bonded to each    other in a state of the zipper being engaged via an easily peelable    plastic layer which is installed in advance on the inside surface of    at least one of the protrusions (hereinafter referred to as the    “third aspect of the present invention”).-   4. In a plastic zipper equipped with a slider, comprising a pair of    male hook and female hook formed on surfaces of plastic films, a    pair of protrusions for slider guide which are installed parallel to    each of the male hook and female hook on the side of the opening    portion, a continuous tightening wall which is parallel to the male    hook and placed inside the male hook and a continuous pressing rib    which is parallel to the female hook and placed inside the female    hook; the pair of protrusions for slider guide are bonded to each    other in a state of the zipper being engaged via an easily peelable    plastic layer which is installed in advance on the inside surface of    at least one of the protrusions and at the same time, the continuous    tightening wall and the continuous pressing rib are bonded to each    other in the state of the zipper being engaged via an easily    peelable plastic layer which is installed in advance on the surface    of at least one of the continuous tightening wall and the continuous    pressing rib (hereinafter referred to as the “fourth aspect of the    present invention”).-   5. In a plastic zipper equipped with a slider, comprising a pair of    male hook and female hook formed on surfaces of plastic films, a    pair of protrusions for slider guide which are installed parallel to    each of the male hook and female hook on the side of the opening    portion; the pair of protrusions for slider guide are bonded to each    other in a state of the zipper being engaged via an easily peelable    plastic layer which is installed in advance on the inside surface of    at least one of the protrusions and at the same time, a top portion    of the male hook and a bottom portion of the female hook are bonded    to each other in a state of the zipper being engaged via an easily    peelable plastic layer which is installed in advance on the surface    of at least one of a top portion of the male hook and a bottom    portion of the female hook (hereinafter referred to as the “fifth    aspect of the present invention”).-   6. In the plastic zipper equipped with a slider as set forth in any    of the preceding items 1 through 5, the color of the surface of the    portions that are bonded to each other comprises two different    colors.-   7. A bag body fitted with the plastic zipper with a slider attached    as set forth in any of the preceding items 1 through 6.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view showing the engagement state of ahermetically-sealable plastic zipper;

FIG. 2 is a cross sectional view showing the disengagement state of ahermetically-sealable plastic zipper;

FIG. 3 is an enlarged cross sectional view showing a continuous pressingrib fitted with an easily peelable plastic layer;

FIG. 4 is an enlarged cross sectional view showing a continuoustightening wall fitted with an easily peelable plastic layer;

FIG. 5 is a cross sectional view showing the engagement state of aconventional plastic zipper;

FIG. 6 is an enlarged cross sectional view showing a female hook fittedon the bottom surface with an easily peelable plastic layer;

FIG. 7 is an enlarged cross sectional view showing a male hook fitted onthe top surface with an easily peelable plastic layer;

FIG. 8 is an enlarged cross sectional view showing a pair of protrusionsfor slider guide that are fitted on each of surfaces with an easilypeelable plastic layer;

FIG. 9 is a perspective view showing one example of well-known plasticzipper imparted with high hermetical-sealability and/or function ofdetecting unsealing;

FIG. 10 is a cross sectional view taken along line A–A′ of FIG. 9;

FIG. 11 is a perspective view showing one example of well-known plasticzipper imparted with high hermetical-sealability and/or function ofdetecting unsealing;

FIG. 12 is a cross sectional view taken along line B–B′ of FIG. 11;

FIG. 13 is a perspective view showing one example of well-known plasticzipper imparted with high hermetical-sealability and/or function ofdetecting unsealing;

FIG. 14 is a perspective view showing one example of well-known plasticzipper imparted with high hermetical-sealability and/or function ofdetecting unsealing;

FIG. 15 is a cross sectional view showing one example of slider for ahermetically-sealable plastic zipper; and

FIG. 16 is a cross sectional view showing the engagement state of ahermetically-sealable plastic zipper according to the present invention.

The symbols in the drawings shall have the following designations:

-   1-1: male hook-   1-2: continuous tightening wall-   1-3: female hook-   1-4: continuous pressing rib-   G-1: protrusion for slider guide-   G-2: protrusion for slider guide-   A-1: easily peelable plastic layer-   B-1: easily peelable plastic layer-   5-1: female hook-   5-2: male hook-   A-5: easily peelable plastic layer-   B-5: easily peelable plastic layer-   A-8: easily peelable plastic layer-   B-8: easily peelable plastic layer-   9-1: slider-   9-2: zipper-   9-3: bag-   9-4: cover film-   9-5: perforated line-   11-4: partition film-   11-5: perforated line-   13-1: spot welding-   14-4: top portion of zipper-   14-5: perforated line-   15-1: inside guide of slider

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

The embodiments of the present invention will be described in moredetail with reference to the attached drawings.

FIG. 1 and FIG. 2 are a cross sectional view showing the engagementstate and disengagement state, respectively of the zipper as describedin Japanese Patent Registration No. 2,938,784 (hereinafter referred toas “hermetically-sealable zipper”). The hermetically-sealable zipper isa plastic zipper comprising a pair of male hook and female hook formedon surfaces of plastic films, a continuous tightening wall 1-2 which isparallel to the male hook 1-1 and placed inside said hook and acontinuous pressing rib 1-4 which is parallel to the female hook 1-3 andplaced inside said hook, so that the zipper is imparted with persistenthermetical-sealability and also impact resistance to a high degree bythe tight contact between the continuous tightening wall and thecontinuous pressing rib as well as self-tightening effect thereof. Thehermetically-sealable plastic zipper is almost free from performancevariation due to temperature variation, and accordingly is well suitedfor packaging liquid and the like. Therein, symbols G-1 and G-2 are eacha protrusion for slider guide.

As an example of sliders not impairing the hermetical sealability of ahermetically-sealable zipper, there is available a slider as describedin Japanese Patent Application No. 316469/1999 (Heisei 11). Asillustrated in FIG. 15, the hermetically-sealable plastic zipper can beopened and closed by that an inside guide 15-1 of the slider slides onthe portion encompassed with the protrusions G-1 and G-2 for sliderguide and the hooks on the opening side of the zipper, and that anoutside guide 15-2 of the slider slides on the outside of the zipper.

In the first aspect of the present invention, the continuous tighteningwall and the continuous pressing rib are bonded to each other in a stateof the zipper being engaged via an easily peelable plastic layer whichis installed in advance on the surface of at least one of the continuoustightening wall and the continuous pressing rib.

FIG. 3 and FIG. 4 are an enlarged cross sectional view showing acontinuous pressing rib and a continuous tightening wall, respectively,and FIG. 16 is a cross section view showing the continuous pressing riband the continuous tightening wall in an engagement state. In FIG. 3 theeasily peelable plastic layer A-1 is installed on a surface of thecontinuous pressing rib 1-4, while in FIG. 4 the easily peelable plasticlayer B-1 is installed on a surface of the continuous tightening wall1-2. However, the easily peelable plastic layer need not be installed onboth the continuous pressing rib and the continuous tightening wall, butmay be installed on either of them only. As illustrated on FIG. 16, thecontinuous pressing rib and the continuous tightening wall are bonded toeach other in a state of the zipper being engaged via an easily peelableplastic layer.

In the following, some description will be given of the second aspect ofthe present invention with reference to FIG. 5, FIG. 6 and FIG. 7.

FIG. 5 is a cross sectional view showing the engagement state of aconventional plastic zipper comprising a male hook 5-2 and a female hook5-1. In the second aspect of the present invention, as illustrated onFIG. 6 which is an enlarged cross sectional view showing a female hook,an easily peelable plastic layer A-5 is installed on the bottom surfaceof the female hook 5-1, while as illustrated on FIG. 7 which is anenlarged cross sectional view showing a male hook, an easily peelableplastic layer B-5 is installed on the top surface of the male hook 5-2.However, the easily peelable plastic layer need not be installed on boththe bottom surface of the female hook and the top surface of the malehook, but may be installed on either of them only.

The top surface of the male hook and the bottom surface of the femalehook are bonded to each other in a state of the zipper being engaged asillustrated on FIG. 5 via an easily peelable plastic layer.

In the following, some description will be given of the third aspect ofthe present invention with reference to FIG. 8. In the third aspect ofthe present invention, an easily peelable plastic layer is installed onthe surface of at least one of the protrusions G-1 and G-2 for sliderguide that are set up on a hermetically-sealable zipper and conventionalplastic zipper as illustrated on FIG. 1 and FIG. 5. FIG. 8 is anenlarged cross sectional view showing only the protrusions for sliderguide, wherein easily peelable plastic layers A-8 and B-8 are installedon the surfaces of the protrusions G-1 and G-2, respectively. However,the easily peelable plastic layer need not be installed on both theprotrusions, but may be installed on either of them only. Thus both theprotrusions are bonded to each other in a state of the zipper beingengaged via an easily peelable plastic layer.

The fourth aspect of the present invention comprises the embodiments ofboth the first and third aspects of the present invention, that is, apair of protrusions for slider guide are bonded to each other via aneasily peelable plastic layer and at the same time, the continuoustightening wall and the continuous pressing rib are bonded to each othervia an easily peelable plastic layer.

The fifth aspect of the present invention comprises the embodiments ofboth the second and third aspects of the present invention, that is, apair of protrusions for slider guide are bonded to each other via aneasily peelable plastic layer and at the same time, a top portion of themale hook and a bottom portion of the female hook are bonded to eachother via an easily peelable plastic layer.

By the term “easily peelable plastic layer” as mentioned herein isgenerally meant a heat-sealed plastic layer having a peel strength of atmost 0.6 kgf/15 mm as measured by the method described in JIS Z 0238. Inthe present invention, the peel strength after the adhesion between theeasily peelable plastic layer to be installed in advance and a companionresin to be bonded therewith is properly at most 0.6 kgf/15 mm,preferably at most 0.3 kgf/15 mm in particular. Therein in the casewhere the easily peelable plastic layers are placed in advance on bothsides, the companion resin is an easily peelable plastic layer, while inthe case where the easily peelable plastic layer is placed in advance oneither side only, the companion resin is a resin which constitutes azipper and a protrusion for slider guide. When peel strength thereinexceeds 0.6 kgf/15 mm, a big force is necessary for opening and closingoperations for a zipper, thereby the protrusions for slider guide aresometimes deformed and inconvenience or trouble in opening and closingoperations for a zipper are caused. Needless to say, however, a peelstrength sufficient for preventing easy peeling is necessary in the casewhere a zipper is placed in an ordinary state without receiving a forcein particular.

The materials which constitute the above-described easily peelableplastic layers are not specifically limited, but exemplified by resincompositions that are usually employed as easily peelable plastics suchas polybutene, ethylene/vinyl acetate copolymer,polyethylene/polypropylene mixture and resin mixtures containing theseresins. With regard to the mechanism of easy peelability, interfacialpeeling is excellent as compared with cohesive peeling in terms ofpreservation of hermetical sealability at the time of opening/closing azipper after unsealing.

The heat seal temperature of the easily peelable plastics is preferablylower than the melting point of the resin constituting the zipper.

In the case of heat sealing a bag body fitted with a zipper in whichpart thereof is bonded in a state of the zipper being engaged via aneasily peelable plastic layer, there is usually adopted without specificlimitation, a method in which a prospective content is filled in the bagbody through the bottom thereof in a state of the zipper being engagedand thereafter, the filling port is heat sealed (hereinafter the bag isreferred to as “bottom opened bag”).

A method for bonding part of a zipper by means of an easily peelableplastic layer may be properly optionally selected in accordance with thephysical properties of the layer to be used from among a heat sealingmethod using a hot air nozzle, a method using a heat sealing hot plate,a method using a ultrasonic heat sealing machine, a method using ahigh-frequency heat sealing machine and the like.

In regard to the timing of adhesion with the easily peelable plastic, itis preferably put into practice at the time of producing a bag bodyfitted with a zipper by the use of a bag making machine in the case of abottom opened flat bag or the like, while in the case of a gusset bag orthe like, it follows that adhesion is conducted after the prospectivecontent is filled in the bag by using a heat sealing machine attached toa filling machine.

On the portion to be bonded using the easily peelable plastic layer, bytaking a bicolor system, that is, making the color of the easilypeelable plastic layer to be installed in advance different from thecolor of a companion resin to be bonded therewith, it is enabled toimpart the function capable of detection of having been unsealed aftersealing packaging. Therein in the case where the easily peelable plasticlayers are placed in advance on both sides, the companion resin is aneasily peelable plastic layer, while in the case where the easilypeelable plastic layer is placed in advance on either side only, thecompanion resin is a resin which constitutes a zipper and a protrusionfor slider guide. In the case of selecting yellow and blue as bicolor,the adhesion portion in a state of bonded (heat sealed) assumes green,but turns yellow and blue after peeling, and never returns to greenunless adhesion (heat sealing) procedure is carried out again, therebyclarifying the fact of having been unsealed.

In the case of the first and second aspects of the present inventionwhere adhesion of the zipper is made via the easily peelable plasticlayer, the color change is somewhat difficult to observe in a state ofthe zipper being closed. However in the case of the third to fifthaspects thereof where adhesion of the protrusions is made via the easilypeelable plastic layer, the color change is remarkably observed.

In the case where the easily peelable plastic layer is placed in advanceon either side only, it is preferable that the companion resin foradhesion which constitutes the zipper and/or protrusions for sliderguide be colored on the surface portion thereof alone, since change incolor tone due to peeling becomes easier to observe.

Implementation methods for opening the bag body fitted with the zipperbonded via the easily peelable plastic layer by the use of the sliderinclude a method wherein the zipper is completely opened, including theadhesion portion via the easily peelable plastic layer and a methodcomprising regulating the size of the inside guide of slider 15-1 asillustrated on FIG. 15, so that even when the slider is brought to thefully open position, the zipper is partially opened, whereas theadhesion portion via the easily peelable plastic layer remains unopened;opening the adhesion portion for the first time by opening part of thezipper with fingertip so as to enable free opening and closing with theslider after the zipper is once opened. Of these, the latter method canexhibit the effect on detecting unsealing as well.

In the following, the present invention will be described in more detailwith reference to comparative example and working examples, whichhowever shall never limit the present invention thereto.

EXAMPLE 1

There was prepared a hermetically-sealable zipper as illustrated on FIG.1 and FIG. 2 the material of which was LLDPE (linear low densitypolyethylene resin), which measured 3.9 mm in width and 2.6 mm inthickness in engaged state, and was in the form of tape (hereinafterreferred to as “sealed zipper-1”), by providing a female zipper (theportion comprising female hooks, a flange and a protrusion for sliderguide each on the side having female hooks) which was coloredtransparent-yellow; a male zipper (the portion comprising male hooks, aflange and a protrusion for slider guide each on the side having malehooks) which was colorless transparent; a transparent-blue easilypeelable plastic layer the material of which was a mixture of LLDPE,ethylene/vinyl acetate copolymer and polybutene, which measured 10 μm inthickness, and which had a peel strength regulated to 0.31 kgf/15 mm,and which was placed on the surface of a continuous tightening wall asillustrated on FIG. 4; content side flange portions measuring 300 μm inthickness and 10 mm in width; opening side flange portions measuring 300μm in thickness; protrusions which measured 1.5 mm in length and 0.8 mmin height, and which was positioned at 1.9 mm from the female hooks onboth the male and female flanges; and further a transparent-blue easilypeelable plastic layer the material of which was a mixture of LLDPE,ethylene/vinyl acetate copolymer and polybutene, which measured 10 μm inthickness, and which had a peel strength regulated to 0.31 kgf/15 mm,and which was placed as illustrated on FIG. 8 but only on the insidesurface of the protrusions on the male hook side so that the continuoustightening wall and continuous pressing rib were bonded to each othervia the easily peelable plastic layer in a state of the zipper beingengaged.

Subsequently, there were prepared bottom opened flat bags which measured140 mm in width and 200 mm in height by dry laminating a LLDPE film, analuminum foil and a polyamide resin film having a thickness of 60 μm, 12μm and 15 μm, respectively, from the inside towards outside of aprospective bag so as to form a laminate film, bonding through heatsealing, the flange portions of the sealed zipper-1 in a width of 4 mmto the inside of the resultant laminate film and thereafter heat sealingboth the ends through heat sealing in a width of 4 mm. Then a slider wasattached to the top of the bag thus prepared and thereafter the insideportion of the protrusions out of contact with the slider on the top endof the sealed zipper was heat-sealed. As a result, the heat-sealedportion turned green.

Subsequently, the sealed zipper was opened by operating the slider,whereupon the green color disappeared on the protrusions (and the jointof the continuous tightening wall and continuous pressing rib), wherebyseparation into blue and yellow was visualized. Thereafter, the sealedzipper was closed by operating the slider, whereupon green colorlinearly remained in part, but never returned to the original greencolor of the time of the adhesion. Thereby it was made possible toconfirm the function of detecting unjust unsealing.

The above-mentioned bottom opened flat bags which each measured 140 mmin width and 200 mm in height and which were each fitted with the sealedzipper with a slider attached were prepared in 20 numbers.

Comparative Example 1

Two sheets of tapes the material of which was LLDPE and which measured300 μm in thickness in and 15 mm in width were interposed, one end ofthe tapes was heat sealed each other in a width of 4 mm, and the otherend thereof was heat sealed in a width of 4 mm onto the inside of the alaminate film whose material and size were the same as those of the filmwhich had been used for the preparation of the above-mentioned bottomopened flat bags each fitted with the sealed zipper with a sliderattached. Thereafter both the ends were heat sealed in a width of 4 mm.

As a result, the bottom opened flat bags which each measured 140 mm inwidth and 200 mm in height and which were each sealed at the three sidesincluding the top portion and both the sides were prepared in 20numbers.

Nitrogen gas at a relative humidity of 50% in a volume of 700 milliliter(ml) was filled in each of the bags which had been prepared in Example 1and Comparative Example 1, respectively so that the nitrogen gas wasenclosed inside the bags by heat sealing the bottom portion in a widthof 4 mm. Then, 10 bags×2 types of nitrogen-filled bags out of these 20bags×2 types thereof were each used to measure the initialconcentration, and the remaining bags were allowed to stand in a steelbox which was filled inside with oxygen gas at ordinary temperature,atmospheric pressure and a relative humidity of 50% for 100 hours andthereafter, were subjected to the measurement of oxygen concentration ofthe nitrogen gas inside the bags. The results are given in Tables 1,where no significant difference was recognized in oxygen permeationamount between the bags of Example 1 and Comparative Example 1, wherebyit was confirmed that the sealed zipper of Example 1 had hermeticalsealability comparable to that of the heat seal of Comparative Example1.

In addition, it was confirmed that after once opened, the sealed zipperexhibited the functions of a hermetically-sealable zipper for generalpurpose.

EXAMPLE 2

There was prepared a colorless transparent hermetically-sealable zipperas illustrated on FIG. 1 and FIG. 2 the material of which was LLDPE(linear low density polyethylene resin), which measured 3.9 mm in widthand 2.6 mm in thickness, and was in the form of tape (hereinafterreferred to as “sealed zipper-2”), by providing content side flangeportions measuring 300 μm in thickness and 10 mm in width; opening sideflange portions measuring 300 μm in thickness; protrusions whichmeasured 1.5 mm in length and 0.8 mm in height, and which was positionedat 1.9 mm from the female hooks on both the male and female flanges;easily peelable plastic layers as illustrated on FIG. 3 and FIG. 4 onthe surfaces of both a continuous pressing rib and a continuoustightening wall and further; easily peelable plastic layers asillustrated on FIG. 8 on the inside surfaces of both the protrusions,each of which layers measured 10 μm in thickness, was made of a mixtureof LLDPE, ethylene/vinyl acetate copolymer and polybutene, and had apeel strength regulated to 0.25 kgf/15 mm, wherein either the continuouspressing rib side or the continuous tightening wall side and either ofboth the protrusions insides were colored transparent-yellow, and theothers were colored transparent-blue, and by bonding the continuoustightening wall and continuous pressing rib to each other via the easilypeelable plastic layer in a state of the zipper being engaged, so thatthe color of the adhesion portion turned green.

Subsequently, there were prepared bottom opened flat bags which measured140 mm in width and 200 mm in height in the same manner as in Example 1,and by the use of the sealed zipper-2 thus prepared, a slider wasattached to the top of the bag thus prepared and thereafter the insideportion of the protrusions out of contact with the slider on the top endof the sealed zipper was heat sealed. As a result, the heat-sealedportion turned green.

Subsequently, the sealed zipper was opened by operating the slider,whereupon the green color disappeared on the protrusions, wherebyseparation into blue and yellow was visualized. Thereafter, even whenthe sealed zipper was closed by operating the slider, the color neverreturned to the original green color of the time of the adhesion.Thereby it was made possible to confirm the function of detecting unjustunsealing. Moreover, by opening the sealed zipper the green color on thejoint of the continuous tightening wall and continuous pressing ribdisappeared, whereby separation into blue and yellow was visualized.

The above-mentioned bottom opened flat bags which measured 140 mm inwidth and 200 mm in height and which was fitted with the sealed zipperwith a slider attached were prepared in 20 numbers. Subsequently, oxygenpermeation amount was measured in the same manner as in Example 1. Theresults are given in Table 1, thus enabling to confirm that the sealedzipper of Example 2 had hermetical sealability comparable to that of theheat seal of Comparative Example 1.

TABLE 1 Example 1 Comp. Example 1 Example 2 Average Standard AverageStandard Average Standard value Deviation value deviation valuedeviation Number of samples 10 10 10 10 10 10 Oxygen initial 0.036 0.0060.036 0.005 0.036 0.005 conc (%) after 100 Hr 0.789 0.113 0.731 0.1210.764 0.108 Remarks Comp.: Comparative, conc.: concentration

INDUSTRIAL APPLICABILITY

According to the present invention, it is made possible to provide a bagbody fitted with a zipper with a slider attached which bag body iscapable of assuring high hermetical-sealability enabling long-termpreservation of contents therein, is easy to open, and is imparted witha function of revealing unjust unsealing as well, since a pair of maleand female hooks and/or protrusions for slider guide are bonded viaeasily peelable plastic layers.

1. A highly hermetically-sealable plastic zipper equipped with a slider,comprising a pair of male hook and female hook formed on surfaces ofplastic films, a pair of protrusions for slider guide which areinstalled parallel to each of the male hook and female hook on the sideof the opening portion, a continuous tightening wall which is parallelto the male hook and placed inside the male hook and a continuouspressing rib which is parallel to the female hook and placed inside thefemale hook, wherein the pair of protrusions for slider guide are bondedto each other in a state of the zipper being engaged via an easilypeelable plastic layer which is installed in advance on the insidesurface of at least one of the protrusions and at the same time, thecontinuous tightening wall and the continuous pressing rib are bonded toeach other in a state of the zipper being engaged via an easily peelableplastic layer which is installed in advance on the surface of at leastone of the continuous tightening wall and the continuous pressing rib.2. The highly hermetically-sealable plastic zipper equipped with aslider as set forth in claim 1, wherein the color of the surfaces of theportions that are bonded to each other comprises two different colors.3. The highly hermetically-sealable plastic zipper equipped with aslider as set forth in claim 1, wherein the easily peelable plasticlayer at the portion bonded via an easily peelable plastic layer whichis installed in advance has a peel strength of at most 0.3 kgf/15 mm. 4.A bag body fitted with a plastic zipper with a slider attached as setforth in claim 1.